Heat exchanger



T. F. PAULS HEAT EXCHANGER Sept. 12, 1961 2 Sheets-Sheet 1 FIG. 5

Filed June 5, 1957 FIG. 2

FIG!

IIIIIIJIII "III,

ATTORNEYS Sept. 12, 1961 Filed June 3, 1957 T. F. PAuLs 2,

HEAT EXCHANGER 2 Sheets-Sheet 2 B3GO INVENTOR.

THERON F. PAULS BY M kw gg I ATTOR rate This invention relates to a heatexchanger construction and more particularly to the art of manufacturinga multiple parallel tube type of heat exchanger unit.

A commonly used and effective type of heat exchanger construction forevaporators, air conditioners, condensers, internal engine coolingradiators, such as automobile radiators, or for space heating such assteam radiators, and the like, is formed of sheet metal and includes anumber of conduits generally in a parallel spaced arrangement extendingfrom a first or intake header to a second or outlet header. One or moreof such sheet metal units may be employed; and the conduits or tubesserve to carry within a confined heat exchange medium such as water,steam, refrigerant cooling, or the like, in conductive relationship withanother medium such as air or other gas passing between the tubes. Thistype of construction fabricated from sheet metal is typical ofautomobile radiators, for example, where the heated water issues fromthe cooling block of the engine with the aid of a pump, first enters oneof two headers, and then through a great number of thin-walled,relatively flat, closely spaced tubes between which cooling air is blownand which extends usually vertically from one to the other headers.Condensers are also frequently of this same type of construction.

According to one heretofore known method of manufacture illustrated inU.S. Patent 2,690,002, this type of heat exchanger unit may be readilymanufactured to provide a great multiplicity of tubes in a sheet ofmetal. This method involves emplacement of a suitable predeterminedpattern of weld preventive between component sheets, pressure welding inall adjoining areas except at the preventive, and inflation along thepreventive to erect tubes integral with the resultant tubed plate. Fulladvantage heretofore has not been taken of this method inasmuch as thetubes formed are of rather fiat or oval shape with the major dimensionslying within or parallel to the metal plate in which the tubes areformed. In many applications it is desired that the tubes extend notonly longitudinally but also extend perpendicularly out of the plate toa considerable extent so as to place a greater number of the tubes inspaced parallel relationship rather than a lesser number in the sameplane. This design adapts the units to fabrication as single pieces oflarge size, a lesser number of which may then be put together forinstallations where the external medium passes through perforations ofthe plate transversely to it rather than passing parallel to the platealong its surfaces.

Therefore, it is an object of this invention to provide a novel andimproved heat exchanger unit free from the aforementioned disadvantagesof complex and consuming constructions and a new and improved method ofconstructing the same. A further object of this invention is to providea heat exchanger unit in which a great number of fluid conduits areintegrated into a single structural member relatively free from seamsand joints and hence a unit admirably suited to mass production methods.Another object of this invention is to provide an improved heatexchanger core structure having closely spaced sheet metal elementscontaining both advantageously angled tubes and also integral extendedsecondary surfaces or fins and all of a construction adapted for themost economical mass production methods of assembling the core. Otherobjects and advantages will be apparent and the invention will be betterunderstood from the following description when read with reference tothe accompanying drawings, in which:

FIGURE 1 is a perspective view of a portion of a typical pressure weldedblank made according to the afore mentioned U.S. Patent 2,690,002 andillustrating a preliminary construction from which the finished units ofthis invention may be most readily and advantageously fabricated;

FIGURE 2 is a perspective View of an adjoining fragment of the sheetmetal unit in a subsequent stage of fabrication still according to theaforementioned prior art patent;

FIGURE 3 is a perspective view of another adjoining fragment of the unitprocessed in accordance with one embodiment of this invention to providea new and improved tube shape;

FIGURE 4 is a transverse cross sectional view corresponding to the endview of FIGURE 1 but showing another embodiment in accordance with thisinvention;

FIGURES is a transverse cross sectional View showing another partiallylaminated sheet blank at a preliminary stage according to the invention;

FIGURE 6 is another transverse cross sectional view showing a laterstage of manufacture of the embodiment of FIGURE 5;

FIGURE 7 is a side elevational view of a portion of the embodiment ofFIGURES 5 and 6 shown in still further progressive stages of manufactureshowing the full development of one form of fin structure;

FIGURE 8 is a side elevational view of the upper portion of anotherembodiment of the form of a panel including a header; and

FIGURE 9 is a fragmentary cross sectional plan View taken 011- lineIX-IX of FIGURE 8.

In accordance with this invention blank sheet metal panels or plateshaving relatively shallow passageways and intervening webbing aresubjected to a reduction in thickness, such as by swaging, between thepassageways in such a manner as to reshape the passageways to more fullyextend them out of the plane of the seat. The resultant tubes are ofrelatively oblong shape extending at right angles to the heat exchangepanel from which the tubes are formed integrally along the panel.Reshaping is accomplished by a swaging, coining or forging operationwhich thins'the metal between the tubes and narrows the dimension of thetubes or passageways in the plane of the panel or sheet while at thesame time tending to extend the dimension of the tube protruding beyondor out of the plane of the panel, but without any attendant reduction inthe overall width of the initial blank. As a result the major axis ofthe tube cross section is put at an angle of about The panel ispreferably of the type obtained in accordance with the teachings of theaforementioned U.S. Patent 2,690,002 wherein the passageways inembryonic form are defined by an included thin layer or stratum of weldpreventing material such as graphite or the like. For the purpose ofproviding integral fins closely and most advantageously associated withthe tubes, the pressure welded panels also include preferably anintervening unwelded area defined by weld preventive extending betweenthe tube forming laminated portions but spaced therefrom. Thisintervening unbonded area is subjected to the aforementioned thinningand may lie in one or more strata to provide two or more thin fins togive a very large extended secondary heat exchanger surface.

The transverse air duct perforations together with fins are constructedin accordance with this invention by first piercing the sheet in thewebbing between the tubes, but preferably in the vicinity of the thinnedintervening unwelded portions at spaced intervals up and down in thearea between adjacent tube portions of the sheet. Finally, an extrusionpiercing and separating step is accomplished along the interveningunwelded stratum in the sections remaining after the first slitting orpiercing operation so as to separate and twist the fins to put them inthe best heat exchange relationship at an angle to the face of theplate. The swaging, piercing and separating operation of this inventionhas been found to produce an advantageous disposition of the tubes andalso a very thin fin structure between the tubes. The fins are turned soas to be in desired alignment or feathering with respect to the airflow.The resultant additional fins are many times thinner and have a greatlymultiplied efiective area as compared to a single heavy fin.

Where a more greatly extended fin surface is desired a severe extrusionis effected in the piercing operation in the intervening fin area so asto not only thin but also further extend the fins out of the plane ofthe heat exchanger plate.

Each of the resultant plates or units may be used alone or stacked upwith a plurality of like plates to form a heat exchanger core structureof the multiple tube type where the tubes of one plate are staggeredwith respect to the tubes of an adjacent plate and Where-the tubes ofeach plate are juxtaposed opposite the fins of an adjacent plate.

Internal layers of weld preventative such as graphite have been found tofacilitate the thinning and tube reshaping.

In FIGURE 1 there is shown a preferred form of blank 1 suitable forpractice of this invention. It is characterized by a pattern 2 includingcertain unjoined portions between the outer faces of the blank 1 whereatthe blank is laminated so as to include spaced parallel parted orlaminated portions 3 and also intervening and surrounding portions 4 atwhich the blank remains unparted. As shown in FIGURE 2, the partedportions 3 are adapted for development by fluid inflation of internalpassageways 6 forming part of a preliminary conduit system 9 evidencedby corresponding rather shallow bulges 7 and 8 on the surface of theintermediate product 5. Although inflation involving the admission offluid under pressure to the interior surfaces at the lamina 3 whichforces these apart to produce a preliminary distention along theinternal passageways 6 is contemplated as a preferred mode of passagewaygeneration, other flat passageway containing blanks are alsocontemplated. In any event, unparted portions 4 remain undistended andseparate the passageways not only from each other but also from anyintervening opening in the blank.

FIGURE 3 shows the new finished article resulting when the intermediateproduct is worked in accordance with the invention to reduce thethickness of the metal at web 14 driving the metal to narrow theoriginal passage 6 in the plane of the blank while elongating it toprotrude on one side at 17 and on the opposite side at 18 so that thefinished panel contains a finished system of hollows 19 having oblongtube passages 16 disposed transversely to extend out the plane of thepanel considerably beyond the preliminary bulges 7 and 3. At the thinnedweb '14 the panel has been stiffened by work hardening. The swagingoperation preferably compresses the metal most severely at the centralpart of the web 14 so as to force the metal to flow more readily asshown.

In the embodiment of FIGURE 4 the panel web is indented andsimultaneously cut to form an air duct 24 between the oblong tubes 26while forming the conduit system 29 of the panel having protuberance's27 on one side as the leading edge of the tubes and protuberances 28 onthe opposite side as the trailing edge.

In FIGURE 5, another form of roll forged blank 31 is shown also havinginternal separations in spaced parallel relationship at 33 at which thepassageways 46 are to be erected and reshaped to the perpendicularconfiguration seen in the intermediate hollow article shown in FIGURE 6which is ready for finning. The blank 31 difiers from the previous blankchiefly by the inclusion of two strata 35 and 36 of separation in theblank portion 34 intervening the separations at 33 and isolatedtherefrom by the unparted areas 32.

After the blank 31 is forged to the shape shown in FIG- URE 6, which ischaracterized by protruding tube extremities 47 and 48 and by thereadily separable zones 45 and 46, it is then provided with a series ofslits such as 50 in the web 44 running athw-art the tubes 47 and themetal remaining between the slits is twisted and preferably alsoextruded to form the almond shaped openings 55 and transverselyextending crude fin 54 snuck up out of the panel to extend at anydesired angle with it, such as an angle of Finally, laminations 45 and46 of each preliminary fin 54 is opened up to form three finished fins56, 57 and 58 each very thin and also turned at an angle to the finishedpanel now having air ducts 61 and 62 and also 63 and 64 in place of eachof the single openings 55.

It will be understood that while three very thin fins are shown in thisembodiment, each fin portion can remain whole or be subdivided into anynumber of individual fins such as the two shown for example in theembodiment of FIGURE 8 where the panel 71 has many parallel tubes 77,many sets of fins 76 and 73, and also has main openings 75 together withfin openings 79. One end of the panel has a connecting header 72 and asupply or discharge connection 80 which is preferably cut free at 82 and83 from the surrounding panel and rounded to permit coupling with asupply or discharge line such as 102 show in the assembled core ofFIGURE 9.

The heat exchange core consists of a series of panels 71, S1 and 91fastened together and mounted by any suitable means such as fastenermounting the unit on support member 106. The individual tubes 77 ofpanel 71 are in staggered relationship with the tubes 87 of panel 81;and the tubes 97 of adjacent panel 91 in turn are staggered with respectto tubes 87. Thus fins 76 and 78 of panel 71 and its openings 75 and 79are aligned with a tube 87 of panel 81 as well as with the openings andfins 96 and 98 of panel 91. Suitable coupling is made between therespective panel connections 80, 9t) and and pipes such as 102 and 103,for example.

Since many other embodiments may occur to those skilled in the art it isto be understood the foregoing is intended by way of illustration of anembodiment now believed preferred and not as a limitation of the scopeof the present invention except as set forth in the appended claims.

What is claimed is:

'1. In the method of producing a hollow metal heat exchanger from ablank of ductile sheet metal having provided therein a plurality ofinternal passageways coextending with each other in substantially spacedrelationship wherein said passageways have their opposite walls bulgedout of corresponding opposite faces of said blank, the improvementcomprising the step of thinning down and simultaneously elongating theweb portion of said blank between adjacent passageways by compressingsaid web portion to force the metal of said web portion to flow towardsaid adjacent passageways sufiiciently to thereby change the crosssectional configuration of said adjacent passageways so that their axistransverse the plane of said blank is elongated, said step beingperformed while maintaining substantially said spaced relationshipbetween said adjacent passageways.

2. The method of claim 1 wherein the thinning is greatest midway betweenadjacent passageways and tapers toward said midway point from saidadjacent passageways.

3. The process of claim 1 wherein the thinning is sufficient to piercethe metal between the passageway portions to provide apertures throughthe blank.

4. The method of claim 1 including the step of piercing to provide aseries of spaced perforations and integral fins in the thinned areabetween said adjacent passagea first pattern containing a plurality ofspaced internal passageways coextending with each other and a secondpattern in areas between adjacent component sheets spaced from andbetween adjacent passageways, forming a blank by pressure welding saidcomponent sheets in their adjacent areas not separated by said stop-weldmaterial, injecting into the unwelded portion between said sheetsdefined by said first pattern a fluid under sufiicient pressure toexpand and bulge said unwelded portion out of opposite faces of saidblank, thinning down and simultaneously elongating the web portion ofsaid blank by compressing said web portion in the areas thereof betweensaid adjacent passageways and opposite said second pattern with saidcompression being sufiicient to force the metal in said areas of saidweb portion to flow toward said adjacent passageways and to change thecross-sectional configuration of said adjacent passageways so that theiraxis transverse the plane of said blank is elongated, said thinning downand said simultaneously elongating the Web portion of said blank beingperformed while maintaining substantially said spaced relationshipbetween said adjacent passageways.

8. The method of claim 7 including the step of piercing said web portionto provide a series of spaced perforations and integral fins in thethinned area of said web portion between said adjacent passageways witheach of said fins extending between adjacent perforations.

9. The method of claim 8 wherein said assembly comprises at least threecomponent sheets and said second pattern is applied between each saidsheets in overlying stratums to form corresponding stratums of unweldedlaminations in said blank.

10. The method of claim 9 including the combination of steps of turningsaid fins to an angle with the plane of said blank between said adjacentpassagways, and separating adjacent layers of metal opposite saidlamination.

11. The method of claim 10 including .the step of assembling a pluralityof the resultant blanks obtained therein to face-to-face relationshipwith passageways of one of said blanks opposite and extending insubstantially the same direction as the web portion, between adjacentpassageways, of an adjacent similar blank.

12. The method of claim 11 wherein each of said blanks is provided witha header transverse and interconnecting therein said passageways, andincluding the step of interconnecting said headers in the assembly ofsaid blanks, to each other.

13. The method of claim 10 wherein the greatest thinning occurs midwaybetween said adjacent passageways.

References Cited in the file of this patent UNITED STATES PATENTS1,962,954 Gotferje June 12, 1934 2,047,207 Krackowizer July 14, 19362,190,494 Templin Feb. 13, 1940 2,375,334 Valyi May 8, 1945 2,626,130Raskin Jan. 20, 1953 2,662,273 Long Dec. 15, 1953 2,740,188 Simmons Apr.3, 1956 2,759,247 Grenell et al. Aug. 21, 1956 2,856,162 Adams Oct. 14,1958 FOREIGN PATENTS 1,467 Great Britain Jan. 31, 1888 962,430 FranceDec. 12, 1949

